.flex-root {
  .flex {
    display: flex;
    width: 1500px;
    margin: 0;
    padding: 0;
    list-style: none;
  }

  .flex :nth-child(1) {
    flex: 1 1 300px;
  }

  .flex :nth-child(2) {
    flex: 2 2 200px;
  }

  .flex :nth-child(3) {
    flex: 3 3 400px;
  }
}
